1. Field of the Invention
The present invention relates to a method and apparatus for incinerating and gasifying biomass material, and more particularly to such a method and apparatus which generates water gas, gaseous products of pyrolysis, combustible char, and heat, while incinerating such material, said apparatus filtering particulate matter from gases discharged from it.
2. Description of the Prior Art
It is well known to dispose of biomass material by incineration with the production of heat and to pyrolyze various materials to produce char or useful gases. It is also well known to convert solid carbonaceous material into water gas or the like and to pyrolyze solid material for these and related purposes in a moving bed in which gases from one portion of the bed are passed through another portion of the bed.
However, prior art methods and apparatus for these and related purposes have various deficiencies such as being adapted only to one or a limited number of such purposes, emitting particulate matter unless external filtering or precipitating devices are employed, being relatively bulky, requiring complex controls and auxiliary devices, being suited for only one type of feed material, operating only with feed material that is substantially solid and is supplied in relatively large pieces, and generating energy only in the form of heat which is thus not usable in internal combustion engines or at a substantial distance from the apparatus.
These limitations of prior art methods and apparatus are particularly disadvantageous where it is desired to dispose of agricultural waste biomass material such as cotton gin trash, hulls, straw, wood shavings, and the like. The ash from such materials is in relatively small particles which are difficult to eliminate from gaseous products of combustion. This ash also melts at a relatively low temperature so that high temperatures cannot be used to obtain complete combustion. These and other biomass materials contain substantial moisture and have a high ash content so that little heat is generated by their combustion and auxiliary fuels are required for drying and to obtain complete incineration. These materials also vary greatly in composition so that methods and apparatus suited for one type of material do not satisfactorily handle other types. The composition of any one type of agricultural waste usually differs from time to time, particularly as to moisture content, so that a fully effective method or apparatus for only one type must be highly flexible in operation to accommodate the differences in fuel characteristics. Agricultural wastes and other biomass materials are often not free flowing due to their sticky composition and/or relatively light weight so that it is not practical to transport such materials gravitationally during processing.
It is, of course, known to prepare waste material for disposal by prior art methods and apparatus by prior drying and/or compacting of the material. However, such prior processing requires additional equipment and heat, electrical, or mechanical energy. The additional energy is often not in a form which can be generated economically at the site where the waste material accumulates.